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Detailed Reference Information |
Kawamura, S., Balan, N., Otsuka, Y. and Fukao, S. (2002). Annual and semiannual variations of the midlatitude ionosphere under low solar activity. Journal of Geophysical Research 107. doi: 10.1029/2001JA000267. issn: 0148-0227. |
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The annual and semiannual variations of the midlatitude ionosphere under low solar activity are studied using middle and upper (MU) radar (135¿E, 35¿N) incoherent scatter observations and Sheffield University plasmasphere-ionosphere model (SUPIM). The variations of the daytime electron density (Ne) and electron and ion temperatures (Te and Ti) at 200--600 km altitudes measured by the radar under low solar activity (F10.7 ≤ 120) are satisfactorily reproduced for the first time by incorporating the radar measured values of the magnetic meridional neutral wind velocity (Uθ) and northward perpendicular plasma drift velocity (V⊥) into SUPIM that uses mass spectrometer incoherent scatter 1986 (MSIS-86) for neutral densities and neutral temperatures. The study shows that the annual and semiannual variations of the midlatitude ionosphere during daytime at altitudes near and above the ionospheric peak under low solar activity depend more on the direct effect of the neutral wind arising through the changes in ionospheric height than on the indirect effect arising through the changes in thermospheric composition (or atomic to molecular concentration ratio); the indirect effect, however, predominates on the variations at altitudes below the ionospheric peak. The electron temperature (Te) undergoes similar but almost opposite seasonal and semiannual variations as the electron density. The ion temperature (Ti) is closer to neutral temperature than to electron temperature at altitudes up to ~400 km and shows comparatively weak annual and semiannual variations. |
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BACKGROUND DATA FILES |
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Abstract |
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Keywords
Ionosphere, Ionospheric dynamics, Ionosphere, Midlatitude ionosphere, Ionosphere, Plasma temperature and density |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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